Coating compositions comprising mixtures of nitrogen-containing acrylic polymers



United States Patent COATING COMPOSITIONS COMPRISING MIX- TURES OF NITROGEN-CONTAINING ACRYLIC POLYMERS Aloysius N. Walus, Flint, Micln, and James M. Donatello, Wilmington, DeL, assignors to E. I. du Pont de Nemours and Company, Wilmington, Del., 2 corporation of Delaware No Drawing. Filed Sept. 30, 1965, Ser. No. 491,815

Int. Cl. C08f 41/12 US. Cl. 26023 6 Claims ABSTRACT OF THE DISCLOSURE A coating composition in which is film-forming polymer is a blend of (a) 4090% by weight of an acrylic polymer that has pendent amino ester groups; and (b) 50-10% by weight of an acrylic polymer that contains an oxazoline drying oil constituent.

This invention relates to a novel polymeric coating composition for metallic substrates which is particularly useful in the repair of painted metal substrates and more particularly, this invention concerns a pigmented polymeric coating composition useful primarily in automotive refinishing of thermosetting enamel paints and in particular refinishing of acrylic enamel paints.

Prior to this invention, it was extremely difficult and costly to repair thermosetting enamel coatings on metallic substrates which are used on a variety of automobiles manufactured today. Previously, repair of these enamel coatings required roughening of the enamel coat followed by a primer and/or a sealer coat before a repair coat of either an enamel or a lacquer was applied. Moreover, in order to obtain an unnoticeable repair, the entire panel usually had to be refinished. Another method for repairing thermosetting enamels comprised using a nitrocellulose based lacquer which adhered tenaciously to a roughened enamel substrate without using a primer or a sealer coat, but the nitrocellulose repair coating deteriorated quite rapidly upon weathering which made the refinished area noticeable after only a few months exposure. The novel coating composition of this invention provides excellent adhesion to thermosetting enamel substrates without first priming or sealing the surface of the enamel and also has excellent resistance to cracking and good outdoor durability.

The novel coating composition of this invention has as a film-forming component a polymer mixture of (a) 40 to 90% by weight based on the weight of the polymer mixture of Interpolymer A which comprises (1) 75 to 95% by weight, based on the weight of Interpolymer A, of methyl methacrylate units,

(2) less than about 20% by weight of ester units of an tsp-unsaturated carboxylic acid and a C to C saturated aliphatic monohydric alcohol, and

(3) 3 to 25% by weight of monovalent amino-ester radicals which are attached to the carbon atoms of the Interpolymer A backbone and have the formula FORMULA 1 0 H R3 H saunas.

in which R is a hydrogen, benzyl or a C to C alkyl radical, R and R are individually selected from the group of hydrogen, benzyl, aryl or a C to C alkyl radical and R is a hydrogen or a C to C radical;

(b) 60 to by weight based on the weight of the polymer mixture of Interpolymer B which is 3,488,307 Patented Jan. 6, 1970 l) 30 to 70% by weight based on the weight of Interpolymer B of methyl methacrylate units,

{2) less than about 35% by weight of ester units of an IXJS'flJIlSHtUI'HtBd carboxylic acid and C to C saturated aliphatic monohydric alcohol,

(3) less than about 10% by weight acrylonitrile units, and

(4) 15 to 35% by weight of units of a compound having the following structural formula:

FORMULA. 2

in which R is a C to C hydrocarbon group of a saturated or unsaturated fatty acid, R is H, C to C alkyl group or R is H, or a C to C, alkyl group and R is a C to C hydrocarbon group of a saturated or unsaturated fatty acid.

The film-forming polymeric component is made up of a mixture of about 40 to by weight of lnterpolymer A and correspondingly about 60 to 10% of Interpolymer B. Preferably, the mixture contains about 50 to 60% by weight Interpolymer A and 50 to 40% by weight Interpolymer B. One particularly preferred composition contains 55% by weight Interpolymer A and 45% by weight Interpolymer B.

Interpolymer A Interpolymer A is formed by first preparing a carboxylic polymer by conventional methods of solution polymerization containing units of about:

(1) 75 to by weight methyl methacrylate (MMA),

(2) less than about 20% by weight of an ester of an a,fl-unsaturated carboxylic acid and a C to C saturated aliphatic monohydric alcohol, preferred are esters of acrylic acid and methacrylic acid, with the particularly preferred ester being ethyl aerylate (EA),

(3) 1.5 to 15% by weight of an pt-unsaturated carboxylic acid such as methacrylic acid, acrylic acid, cro tonic acid and the like, with methacrylic acid being the preferred constituent.

The carboxylic polymer is then reacted with an aziridine compound, which is often referred to as an alkylene imine, of the following structural formula:

wherein R R R and R are as defined in Formula 1.

Ethylenimine (Formula 4) and 1,2-propylenimine {Formula 5) as shown hereinafter are particularly preferred aziridines useful in this invention because of their relatively low cost and plentiful supply and because they tend to provide the final product with excellent adhesive properties.

The alkylene imine reacts with the acid group of the 10 polymer chain to form pendant monovalent amino-ester radicals as previously shown in Formula 1.

Preferably, Interpolymer A is composed of about 78 to 82% by weight MMA, 12 to 14% by weight EA, and 5 to 8% by weight of monovalent amino ester radicals attached to the polymer backbone which are the reaction products of the carboxyl groups of methacrylic acid and either propylenimine or ethylenimine and have the formula:

FORMULA 6 0 II II II dated-tau in which R is either H or methyl.

One particularly preferred composition of Interpolymer A consists of about 80% by Weight MMA, 13% by weight EA and 7% by weight of the amino ester of methacrylic acid and propylenimine.

Polymerization of the monomers to form the carboxylic polymer is carried out by mixing the monomers with suitable solvents, such as ethyl acetate, isopropyl alcohol, toluene, butyl alcohol and the like. A polymerization catalyst is then added to the mixture, such as tertiary butyl peroxide, cumene hyperoxide, benzoyl peroxide and ambisisobutyronitrile. The amount of catalyst used is about 0.1 to 2% by weight of the monomers present. The reaction mixture is then refluxed until the polymerization is completed which can be checked by a polymer solids determination.

The carboxylic polymer is then reacted with an alkylene imine. In a typical imination reaction, the alkylene imine is mixed with the carboxylic polymer in a reaction vessel under atmospheric pressure. Preferably, the amount of alkylene imine added to the carboxylic polymer is about 25% in excess of the total molar amount of alkylene imine which is necessary to esterify all the pendant carboxyl groups of the polymer to aminoester groups. The mixture is stirred and reacted at about 35 to 90 C. until the reaction is completed (e.g., about /2 hour at the higher temperatures to about 12 hours at the lower temperatures). Finally, the reaction product is cooled to room temperature. The upper temperature limit of the imination reaction is determined largely by the solvents used in the system and vaporization temperature of the imine. The entire reaction can be carried out at room temperature, but heating is much preferred because of the shorter reaction time.

Interpolymer B Interpolymer B is prepared by conventional methods of solution polymerization of monomeric units of about (1) 30 to 70% by weight methyl methacrylate (2) less than about 35% by Weight of an ester of an a ti-unsaturated carboxylic acid and a C to C saturated monohydric alcohol, preferred are esters of acrylic and methacrylic acid with the preferred being ethyl acrylate (3) less than about by weight of acrylonitrile (AN), and

(4) 15 to 35% by weight of a compound as previously defined by the structural Formula 2.

In its preferred form, Interpo-lymer B consists of about 53 to 57% by weight MMA, 13 to 17% EA, 3 to 7% AN, and 23 to 27% of a reaction product of 1 mole of tris-(hydroxymethyl)-aminomethane and 3 moles of tall oil fatty acid which is subsequently reacted with formaldehyde. This compound is currently sold under the trademark of Chemacoil TA 100." In relating the structural Formula 2 to the above reaction product, R is the hydrocarbon group of tall oil fatty acid, R is the hydrocarbon group of a tall oil fatty acid less the CH group, which is adjacent to the carboxyl group of the acid, R is A wide variety of reaction products of aldehydes and esteramides of hydroxy compounds can be used in place of the (4) constituent defined by Formula 2 or in a mixture with compounds of Formula 2. These reaction products which are similar to the Formula 2 compound are prepared according to the disclosure of US. Patent 2,559,440, issued July 3, 1951, which is hereby incorporated by reference.

In both lnterpolymers A and B, up to 15% by weight of units of styrene can be substituted for part or all of the (2) constituent without adversely affecting the properties of the coating composition.

A coating composition is formulated from lnterpolymers A and B by properly blending these constituents to obtain desired film properties. This polymer blend is then pigmented and can be subsequently diluted with solvents to form a lacquer composition.

The coating composition of this invention is preferably pigmented to pigment volume concentration of about 1 to and preferably about 1 to 20%. The term pigment volume concentration is the ratio expressed on a percentage basis of the volume of the pigment relative to the total volume of the non-volatile content of the coating composition including the organic film-forming materials and pigment.

A Wide variety of pigments can be used with the only requirement being that the pigment used does not react with the film-forming polymer. Following are some typically useful pigments: magnesium silicate, zinc oxide, barytes, silica, zinc dust, aluminum (finely divided flakes and powder), titanium dioxide, Wollastonite, carbon black, monastral red, monastral blue, indo blue, chrome yellow, monastral green, copper bronze, green gold, iron oxides and the like.

The following solvents or mixtures thereof are useful for forming a lacquer composition from a pigmented film-forming polymer of this invention: acetone, methylethyl ketone, amyl alcohol, Cellosolve" acetate, ethyl acetate (denatured), ethyl alcohol (denatured), isopropanol, ethylene dichloride, butyl lactate, diacetone alcohol, diisobutyl ketone, cyclohexanone, amyl acetate, butyl Cellosolve, cyclohexanol, methyl acetate, furfural, petroleum naphtha, toluene, cyclohexane, benzene, substituted benzene, substituted toluene, hexane, toluenetype hydrocarbon, aromatic hydrocarbons, high boiling petroleum naphtha, xylene, high solvency petroleum hydrocarbon, diethyl ether, methyl amyl acetate, and butanol. Useful lacquer compositions contain about to 50% by weight organic solvent and 10 to 50% by weight of the film-forming polymer.

A particularly preferred solvent consists of 38% by weight of a mixture of hexane and acetone, 52% by weight of a mixture of isopropyl alcohol, xylene, toluene, butyl alcohol and 10% by weight of a mixture of methylamyl acetate and Cellosolve acetate.

The coating composition of this invention adheres quite well to either butfed or weathered enamel surfaces, but preferably the surface is buffed before the coating is applied. If the coating composition is to be applied over a new or an unweathered enamel, butting is essential for good adhesion. The coating can be applied by handspray or electrostatic spray techniques, or by dip or flow coating. After application, the composition can be air dried or baked at 220 F. for about 20 to 30 minutes.

Another novel feature of the coating composition of this invention is that after the dried coating is exposed to ultraviolet light, for example, sunlight, for about 2 weeks, the polymer cross-links and becomes insoluble in solvents which were used to apply the coating and also become more resistant to cracking upon weathering. The composition before exposure to ultraviolet light acts as a conventional lacquer but after exposure, it has the characteristics of an enamel. This and the other desirable characteristics of the coating composition of this invention make is useful not only for repair and refinishing of enamels, and in particular acrylic enamels, but also as a suitable composition for repairing all types of coated metal substrates, such as metals coated with acrylic lacquers, nitrocellulose lacquers, alkyd-melamine paints and the like. Furthermore, the composition of this invention can be used as the primary topcoat on suitably primed metal substrates.

The examples illustrate the invention. All quantities shown are on a weight basis unless otherwise indicated.

EXAMPLE 1 A coating composition was prepared by formulating two Interpolymers A and B having the following compositions:

Interpolymer A A polymer was formed of methyl methacrylate/ethyl acrylate/methacrylic acid. This polymer was subsequently treated with propylenimine to form pendant aminoester groups on the polymer backbone.

Interpolymer B A polymer was formed of methyl methacrylate/ethyl acrylate/acrylonitrile /Chemacoil TA-100" (described hereinafter) in a weight ratio of 55/ 15/5/25. Preparation of Interpolymer A MMA/EA/MAA-propylene imine Parts by weight Portion 1:

Toluene 1725.0 Anhydrous isopropyl alcohol 1145.0 Ethyl acetate 843.0 Portion 2:

Methyl methaerylate monomer 2245.0 Azobisisobutyronitrile 9.0 Ethyl acrylate monomer 397.0 Methacrylic acid 214.0 Portion 3:

Azobisisobutyronitrile 9.0 Ethyl acetate 30.0 Portion 4:

Azobisisobutyronitrile 10.0 Ethyl acetate 30.0 Portion 5 Ethyl acetate 724.0 Portion 6:

Propylenimine 176.0 Anhydrous isopropyl alcohol 183.0 Portion 7:

Anhydrous isopropyl alcohol 77.0

Total 7817.0

Each of the monomers was of the ordinary commercially available inhibited grade which contains a small amount of inhibitor, such as the methyl ether of hydroquinone.

The multi-component proportions were premixed be fore they were added. Portion 1 was charged into a conventional polymerization vessel equipped with a stirrer, thermometer and means to introduce reagents, and means of heating cooling the reaction mixture and was heated to its reflux temperature of about to 83 C. Portion 2 was premixed just before it was added since it was not stable and was added continuously over a 2 hour period to the reaction vessel while maintaining the temperature of the ingredients at about 80 C. After Portion 2 was added, the reaction mixture was held at this temperature for about 2 hours. Portion 3 was then added with constant agitation while the temperature of the reaction mixture was maintained at about 80 C. and the mixture was held at this temperature for about one hour. Portion 4 was slowly added with constant stirring and Portion 5 was then added while the temperature of the reaction mixture was held at about 70 C. until a Gardner Holt viscosity of Z Z; was reached. Next, Portion 6 was slowly added with constant agitation, then Portion 7 was added and the reaction mixture was held at about 77 C. until the acid number of the mixture reached about I or below. The resulting reaction mixture which had about a 40% solids content was cooled to room temperature and filtered to remove coagulurn formed during the reaction.

Preparation of lnterpolymer B MMA/EA/AN/ChemacoiP TA Parts by weight Portion 1:

Methyl amyl acetate 102.30 Xylol 152.00 Portion 2:

Methyl methacrylate monomer 224.80 Chemacoil TA-IOO (reaction product of one mol of iris (hydroxymethyl) aminomethane with 3 mols of tall oil fatty acid which is subsequently reacted with one mol of formaldehyde using the process of U.S.P. 2,559,440, issued July 3, 1951) 102.20 Cellosolve acetate 74.10 Dicumyl peroxide 410. Acrylonitrile 20.50 Ethyl acrylate monomer 61.30 Di-tertiary-butyl peroxide 6.20 Portion 3:

Toluene 74.10

Total 821.60

The multi-component portions were premixed before they were added. Portion 1 was charged into a conventional polymerization vessel equipped with stirrer, thermometer and means to introduce the reagents, and means of heating and cooling the reaction mixture and was heated with agitation to its reflux temperature which was about 132 C. to 135 C. Portion 2 was premixed only a short time before it was added since it was not stable and was added at an even and continuous rate over a 5hour period with constant agitation while maintaining a reflux temperature of about 132 C. to 133 C. The mixture was held at its reflux temperature until a conversion of about 53.5% polymer solids was reached and a constant viscosity was obtained between 23-24 Gardner Holt viscosity. The mixture was then cooled to room temperature and Portion 3 was added. The resulting mixture which has a solids content of about 40% was filtered to remove coagulum that has formed during the reaction.

An acrylic lacquer was then formulated by forming a pigment dispersion, mixing this dispersion with the blend of Polymers A and B and diluting this mixture to a spray viscosity with solvents.

Formula Y pigment dispersion Parts by weight Interpolymer B solution (50% solids) 188 Titanium dioxide pigment 580 7 Acetone 77 Toluene 129 Cellosolve acetate 26 Total 1000 The ingredients were premixed and charged into a conventional sand-grinding mill and ground to about a 0.3 mil fineness.

The acrylic lacquer was formed by mixing the follow- A coat of the acrylic lacquer about 2 mils in thickness was sprayed onto each of the following sets of panels (15 panels per set): autobody steel panels which had been suitably primed; steel panels coated with acrylic lacquer; steel panels coated with a pigmented nitrocellulose lacquer; steel panels coated with a thermosetting acrylic enamel; steel panels coated with an alkyd enamel; steel panels coated with an alkyd-melamine enamel; the surface of the thermosetting acrylic enamel, the alkyd enamel and the alkyd-melamine enamel were machine buffed with a conventional buffing compound before the acrylic lacquer was applied.

The initial appearance of each of these sets of panels and adhesion of the lacquer to the various substrates was excellent.

Five panels of each of the above sets were subjected to a high-humidity-low temperature crack test which consisted of 24 cycles. In each cycle, the panels were subjeeted to (1) 100% relative humidity and 100 F. for 24 hours, (2) F. for 24 hours and (3) room temperature for 4 hours. At the completion of each cycle, the panels were examined with a magnifying glass for cracks. At the end of the test, many of the above panels showed no cracking, while several had some slight insignificant cracks.

Ten panels of each of the sets were exposed in Florida at a 45 angle facing south. The panels were examined after 6 months and 12 months. After 12 months of weathering, each of the panels showed good color retention, excellent gloss, very little chalking and water spotting, and no loss of adhesion to the substrate.

Both the high humidity-cold crack test and the outdoor exposure test indicate that the novel acrylic lacquer composition of this invention is an excellent primary coating for metals and adheres well to all types of thermosetting enamel substrates even under severe testing conditions.

EXAMPLE 2 xylene and toluene) 22 Di-butyl phthalate 15 Air blown castor oil 11 Total 100 The resulting composition had a solids content of about 45 A pigment dispersion was then formed according to Formula Y pigment dispersion of Example 1 with the exception that the above nitrocellulose solution was substituted for the Interpolymer B solution. This pigment dispersion was then mixed with the above nitrocellulose composition according to the procedure Example 1 to form a pigmented nitrocellulose lacquer.

Four sets (10 panels per set) of suitable primed steel panels were prepared and each set was coated with a different commercially available thermosetting acrylic paint. The following thermosetting acrylic paints were used. Du Pont, Cook, Jones-Dabney and Dizler. Each of the acrylic paint surfaces was first buifed. About a 2 mil coat of the acrylic lacquer of Example 1 was sprayed on 5 panels of each set and air dried. A 2 mil coat of the above prepared nitrocellulose lacquer was sprayed on the remaining 5 panels of each set and air dried. Both the nitrocellulose lacquer coated panels and the acrylic lacquer coated panels had a good appearance and both lacquers had excellent adhesion to the acrylic paint substrate.

All of the panels are then exposed out of doors in Florida at a 45 angle facing south. After 2 months, each panel was checked for appearance and adhesion of the topcoat to the acrylic paint. The results of the test (average of 5 panels) are as follows:

Adhesion/Appearance Example 1 Nitroacrylic cellulose lacquer lacquer Acrylic thcrrnosettiug paint it Punt l0, 'Exccllent 5/Chalked.

Cook Joues-Dabney. do fi chalked. Dizler .110 T/Chalked.

1 No lacquer remained on the panels. Adhesion rating, 10=Excellent adhesion; 0=N0 adhesion.

The above test illustrates the superiority of adhesion and appearance of the acrylic lacquer composition of this invention in comparison to conventional nitrocellulose lacquers which are frequetly used to repair acrylic paints.

EXAMPLE 3 Parts by weight Methylmethacrylate solution (40% solids) 101 Cellulose acetate butyrate (25% solids) 120 Butyl cyclohexanol phthalate ll Coconut oil modified glycerol phthalate solids) 18 Total 250 The resulting polymer solution had a solids content of about 45%.

A pigment dispersion was formulated which was the same as Formula Y pigment dispersion of Example 1 except an equivalent amount of the aforementioned methyl methacrylate solution was substituted for the Interpolymer B solution of Example 1. An acrylic lacquer was then formulated according to Example 1 except the above prepared pigment dispersion and polymer solution were used.

Ten steel panels were primed and coated with a thermosetting acrylic enamel paint and the coating was buffed. A 2 mil thick coat of the acrylic lacquer composition of Example 1 was applied to 5 of the panels and allowed to air dry. Similarly, a 2 mil thick coating of the above conventional acrylic lacquer was applied to the remaining 5 panels and air dried.

After 72 hours, each of the panels was checked for adhesion of the topcoat. The adhesion test involved cutting diamond shapes on the paint in which the cut penetrated the paint film to the metal, then a piece of tape was placed over the cut area and smoothed down. The tape was then removed. If none of the topcoat was removed, the adhesion of the lacquer was considered excellent. Each of the panels coated with the acrylic lacquer composition of Example 1 had excellent adhesion to the acrylic paint while the conventional acrylic lacquer readily peeled off the acrylic enamel.

EXAMPLE 4 The following acrylic lacquers were prepared according to Example 1 using the Formula Y pigment dispersion with the exception that the polymer proportions as indicated were used to form the lacquer:

(Interpolymcr C was prepared using the procedure of Example 1 to form Interpolymer A, except methyl methacrylate/methacrylic acid in a weight ratio 0! 93/7 was used to form the polymer which was subsequently reacted with propyleuimine.)

4 Interpolymer C 80 Interpnlyrner 13 (Ex. 1)

5 Interpolymer C 48 Interpolymer B (Ex. 1). 52

A coating of about 2 mils of each of the above acrylic lacquers 1-5 was sprayed onto separate steel panels, each panel having a buffed acrylic paint coating and the acrylic lacquer was allowed to air dry. The initial appearance and adhesion of the lacquer was excellent. In each case, the results of the high humidity-low temperature crack test as described in Example 1 were similar to those obtained for the acrylic lacquer of Example 1. Also, each of the acrylic lacquer coatings showed excellent outdoor durability even after long periods of exposure.

EXAMPLE 5 An acrylic lacquer was prepared by first forming the following interpolyrners:

Interpolymer C-Prepared in Example 4.

Interpolyrner DWas prepared using the procedure of Example 1 to form Interpolymer B, except methyl methacrylate/"Chemacoil TA-lOO (described in Example 1) in a weight ratio of 70/30 was used to form the polymer.

A pigment dispersion was formulated which was the same as Formula Y pigment dispersion of Example 1 except that the above Interpolymer D was substituted for the Interpolymer B of Example I. A lacquer was then formulated according to Example 1, except the above prepared pigment dispersion and interpolymers were used.

Five steel panels were primed and coated with a thermosetting acrylic enamel paint and the coating was buffed. A 2 mil coat of the above lacquer was applied and air dried. The initial appearance and adhesion of the lacquer was excellent. The results of the high humidity crack test as described in Example 1 were similar to those obtained for the acrylic lacquer of Example 1. Also, the lacquer showed excellent outdoor durability even after a long period of exposure.

We claim:

1. A coating composition in which the filrn-forming compenent comprises a polymer mixture which consists essentially of (a) 40 to by weight based on the weight of the polymer mixture of Interpolymer A which consists essentially of (1) 75 to by weight based on the weight of said Inter-polymer A of methyl methacrylate units,

(2) less than about 20% by weight of ester units of an a,,8-unsaturated monocarboxylic acid and a C3 to C saturated aliphatic monohydric alcohol,

(3) 3 to 25% by weight of monovalent aminoester radicals attached to the carbon atoms of the interpolymer backbone of the formula wherein R is selected from the group consisting of hydrogen, benzyl and C to C alkyl radicals, R and R are selected individually from the group consisting of hydrogen, benzyl, aryl and C to C alkyl radicals, and R is selected from the group consisting of hydrogen and C to C alkyl radicals;

(b) 60 to 10% by weight based on the weight of the polymer mixture of lnterpolymer B which consists essentially of (1) 30 to 70% by weight based on the weight of said Interpolymer B of methyl methacrylate units,

(2) less than about 35% by weight of ester units of an a,fl-unsaturated monocarboxylic acid and a C to C saturated aliphatic monohydric alcohol,

(3) less than about 10% by weight of acrylonitrile units, and

(4) 15 to 35% by weight of units of a compound having the following structural formula wherein R is from the group consisting of a C to C hydrocarbon group of a saturated fatty acid and C to C hydrocarbon group of an unsaturated fatty acid, R is from the group consisting of H, C to C alkyl group, and

R is from the group consisting of H, C to C allryl group and R is from the group consisting of C to C hydrocarbon group of a saturated fatty acid and C to C hydrocarbon group of an unsaturated fatty acid.

2. The coating composition of claim 1 containing pigment in a pigment volume concentration of about 1 to 50% and in the polymer mixture which consists essentially of 50 to 60% by weight of Interpolymer A and 50 to 40% by weight Intcrpolymer B.

3. The coating composition of claim 1 in which said monovalent amino-ester radical is of the formula 4. The pigmented coating composition of claim 2 in which said monovalent amino-ester radical is of the formula 5. The coating composition of claim 1 in which R is a tall oil fatty acid chain, R is a tall oil fatty acid chain less a CH;, group, R is H and R is --CHzO-(%Ru 6. A coating composition containing pigment in a pigment volume concentration of 1 to 20%, 10 to 50% by weight based on the weight of the coating composition of a filament-forming component and complementary 90 to 50% by weight of an organic solvent mixture of nonpolymerizable and non-reactive liquids; in which said film-forming component comprises a polymer mixture which consists essentially of (a) 50 to 60% by weight based on the weight of the polymer mixture of an Interpolymer A which consists essentially of (l) 78 to 82% by weight of said Interpolymer A of methyl methacrylate units, (2) 12 to 14% by weight of ethyl acrylate units, (3) to 8% by Weight of monovalent aminoester radicals attached to the carbon atoms in the interpolymer backbone of the formula in which R is from the group consisting of H and methyl;

12 (b) 50 to by weight based on the weight of the polymer mixture of lnterpolymer B which consists of (1) 53 to 57% by weight based on the weight of said Interpolymer B of methyl methacrylate units, (2) 13 to 17% by weight of ethyl acrylate units, (3) 3 to 7% by weight of acrylonitrile units, and (4) 23 to 27% by weight of units of a compound having the structural formula wherein R is a hydrocarbon group of a tall oil fatty acid and R is a hydrocarbon group of a tall oil fatty acid less a -CH group.

References Cited UNITED STATES PATENTS 2,559,440 7/1951 Jordan et a1. 260-4045 3,113,038 12/1963 Lattarulo et al. l17--l40 3,208,981 9/1965 Miranda. et a1. 260-78.5 3,290,416 12/1966 Christensen et a1. 260901 3,309,331 3/1969 McDowell et al. 26029.6

DONALD E. CZAIA, Primary Examiner R. A. WHITE, Assistant Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,488,307 January 6, 1970 Aloysius N. Walus et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 11, line 23, "filament" should read film Column 12, lines 11 to 20, the formula should appear as shown below: 0

CH C O-C--R 2 10 l 3 H C C CH --OC R O N \C I C=CH Signed and sealed this 18th day of August 1970.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR.

Attesting Officer Commissioner of Patents 122233-30 UNITED S'IATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No i' jggs Dated January 97 Inventor(s) Aloysius N. walus and James M. Donatello It is certified that: error appears in the above-identified patent. and that said Letters Patent are hereby corrected as shown below:

Column 11, line 23, "filament" should read film Column 12, Claim 6, lines 11-20, the structurel formula should read:

C i (i CH2 This certificate supersedes Certif August 18, 1970.

icate of Correction issued Signed and sealed this 3rd day of November 1970 (SEAL) Attest: EDWARD M.FLETCHER,JR. Ettesting Officer WILLIAM E. SCHUYLER, JR. Commissioner of Patents 

